Fig. 5

Complement bystander killing of neurons near astrocytes in rat brain following intracerebral AQP4-IgG injection. a AQP4-IgG (15 μg) (or 15 μg control IgG) and dead cell stain EH-1 (6 μM) in a 3-μl volume was injected in cortex and striatum of rat brain, and rats were sacrificed at 90 min. In some studies, rats were injected with Fc hexamer (50 mg/kg, iv) by tail vein 2 h before or MK801 (10 mg/kg, ip) 30 min before intracerebral injection of AQP4-IgG. b Low-magnification micrographs showing dead cells (red EH-1 fluorescence), NeuN (green), and GFAP (blue) for studies done in AQP4^+/+ rats, Fc hexamer-treated AQP4^+/+ rats, and AQP4^−/− rats. c High-magnification confocal images of AQP4^+/+ rat brain at 90 min after injection of AQP4-IgG (or control IgG) and EH-1 showing dead astrocytes and nearby dead injured neurons. Expanded images on the right showing representative fields. Filled arrowheads show dead astrocytes, open arrowheads show nearby dead neurons, and arrow points to a non-neuron, non-astrocyte dead cell. d Rats were injected with MK801 (10 mg/kg, ip) 30 min before intracerebral injection of AQP4-IgG (or control IgG) and EH-1. Imaging showing dead cells (red EH-1 fluorescence), NeuN (green), and GFAP (blue). Filled arrowheads show dead astrocytes, open arrowheads show nearby dead neurons, and arrow points to a non-neuron, non-astrocyte dead cell. Representative of micrographs done on sections from three rats